1. Field of the Invention
The invention relates to a cylindrical plasma resonant cavity used for manufacturing an optical fiber perform using PCVD (Plasma Chemical Vapor Deposition).
2. Description of the Related Art
PCVD (Plasma Chemical Vapor Deposition), a main process for manufacturing an optical fiber preform, has the characteristics of flexibility and accuracy, and a plasma resonant cavity microwave system is a core part of PCVD processing equipment. The plasma resonant cavity microwave system includes three parts: a plasma resonant cavity, a microwave generator, and a waveguide device. Microwaves generated by the microwave generator are coupled to the plasma resonant cavity through the waveguide device, and the high-frequency microwave energy is transmitted to an area for processing an optical fiber preform through the plasma resonant cavity for finishing the PCVD processing. The match between the plasma resonant cavity and microwave is very important in the process. The mismatching between the two not only affects the coupling effect and causes energy loss, but also easily damages the system device, and also affects the machining precision of the PCVD processing.
The conventional plasma resonant cavity used for manufacture of optical fiber preforms includes two different structure types: a coaxial structure type and a cylindrical structure type. The cylindrical structure type is more suitable for processing large-diameter performs using PCVD. The cylindrical resonant cavity is simple in cavity structure, easy for processing and manufacturing, and excellent in deposition performance. However, most conventional resonant cavities adopt fixed structures, the size of the cavity body is fixed, the requirements of deposition of lining pipes with different sizes cannot be met, and the processing range is greatly limited.